A small human named Nicky is taking out the garbage when he spots Ickis, who startles him. Nicky alerts his older brother of this monster, who thinks that Nicky is crazy and just saw a bunny rabbit.
The next day, the Gromble announces to all of his monster students that it is Halloween and that monsters are banned from walking out of the dump, saying that he has three punishments for anyone who disobeys him: "bad", "really bad", and "you don't want to know". Ickis doesn't want to disobey the Gromble, but his roommates, Oblina and Krumm, convince him otherwise.
Out in the city, the trio escapes from the dump and see some kids getting candy. They try to scare the kids, who just think that they're humans in costumes. To blend in with the costumed human kids, the monsters pretend to be trick-or-treaters and crash a Halloween party. Meanwhile, Nicky, who has designed his Halloween costume to look like Ickis, gets separated from Jake and his friends as they start egging and T-P-ing the neighborhood. In the process, one of Jake's friends mistakes Ickis for Nicky, while Krumm and Oblina mistake Nicky for Ickis.
Nicky is taken back to the trio's dorm where they find out Ickis is Nicky in costume, but they are unable to get him back out right now. As a result of the switch, Nicky is taken to Monster Academy, while Ickis, disguised as Nicky, goes to a human school, where he gets detention for talking about the dump when the teacher asks him to tell his classmates about his house. After school, Jake's friends come over to trade their Halloween candy when Ickis attempts to escape. But when Jake rips off Ickis' hat, they get into a fight, which eventually triggers Ickis' scare mode and frightens Jake and his friends. Afterwards, Krumm and Oblina bring Nicky home safely, telling him not to tell anyone else about them, and are then reunited with Ickis.
Back at the Monster Academy, the Gromble reveals that he's now found out that Ickis, Oblina and Krumm did indeed sneak out on Halloween, and at first praises them for doing so. However, he then adds that he still has to punish them for disobeying him, and tells them to select their punishment. Ickis asks what the third punishment, "you don't want to know", is, but the episode ends before the viewers can learn what it is.
Home video releases
- Aaahh!!! Real Monsters: Monsters' Night Out
- Aaahh!!! Real Monsters: Season 1 (both versions)
- Aaahh!!! Real Monsters: The Complete Series
- Out of the Vault Halloween
- This episode was ranked #53 in The 100 Greatest Nicktoon Episodes countdown, and was also the only Aaahh!!! Real Monsters episode to make it into the countdown.